Re: [PATCH] DMA: add a driver for AMBA AXI NBPF DMAC IP cores

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Hi Andriy,

Thanks for the review.

On Mon, 14 Apr 2014, Shevchenko, Andriy wrote:

> On Sat, 2014-04-12 at 19:39 +0200, Guennadi Liakhovetski wrote:
> > This patch adds a driver for NBPF DMAC IP cores from Renesas, designed for
> > the AMBA AXI bus.
> > 
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
> > ---
> > 
> > Tested on a Xilinx zc706-based board with an SD-host (driver will be 
> > submitted shortly) and a PL011 UART.
> > 
> >  Documentation/devicetree/bindings/dma/nbpfaxi.txt |   61 +
> >  drivers/dma/Kconfig                               |    6 +
> >  drivers/dma/Makefile                              |    1 +
> >  drivers/dma/nbpfaxi.c                             | 1554 +++++++++++++++++++++
> >  include/dt-bindings/dma/nbpfaxi.h                 |   20 +
> >  5 files changed, 1642 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/dma/nbpfaxi.txt
> >  create mode 100644 drivers/dma/nbpfaxi.c
> >  create mode 100644 include/dt-bindings/dma/nbpfaxi.h
> > 
> > diff --git a/Documentation/devicetree/bindings/dma/nbpfaxi.txt b/Documentation/devicetree/bindings/dma/nbpfaxi.txt
> > new file mode 100644
> > index 0000000..d5e2522
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/dma/nbpfaxi.txt
> > @@ -0,0 +1,61 @@
> > +* Renesas "Type-AXI" NBPFAXI* DMA controllers
> > +
> > +* DMA controller
> > +
> > +Required properties
> > +
> > +- compatible:  must be one of
> > +               "renesas,nbpfaxi64dmac1b4"
> > +               "renesas,nbpfaxi64dmac1b8"
> > +               "renesas,nbpfaxi64dmac1b16"
> > +               "renesas,nbpfaxi64dmac4b4"
> > +               "renesas,nbpfaxi64dmac4b8"
> > +               "renesas,nbpfaxi64dmac4b16"
> > +               "renesas,nbpfaxi64dmac8b4"
> > +               "renesas,nbpfaxi64dmac8b8"
> > +               "renesas,nbpfaxi64dmac8b16"
> > +- #dma-cells:  must be 2: the first integer is a terminal number, to which this
> > +               slave is connected, the second one is flags. Flags is a bitmask
> > +               with the following bits defined:
> > +
> > +#define NBPF_SLAVE_RQ_HIGH     1
> > +#define NBPF_SLAVE_RQ_LOW      2
> > +#define NBPF_SLAVE_RQ_LEVEL    4
> > +
> > +Optional properties:
> > +
> > +You can use dma-channels and dma-requests as described in dma.txt, although they
> > +won't be used, this information is derived from the compatibility string.
> > +
> > +Example:
> > +
> > +       dma: dma-controller@48000000 {
> > +               compatible = "renesas,nbpfaxi64dmac8b4";
> > +               reg = <0x48000000 0x400>;
> > +               interrupts = <0 12 0x4
> > +                             0 13 0x4
> > +                             0 14 0x4
> > +                             0 15 0x4
> > +                             0 16 0x4
> > +                             0 17 0x4
> > +                             0 18 0x4
> > +                             0 19 0x4>;
> > +               #dma-cells = <2>;
> > +               dma-channels = <8>;
> > +               dma-requests = <8>;
> > +       };
> > +
> > +* DMA client
> > +
> > +Required properties:
> > +
> > +dmas and dma-names are required, as described in dma.txt.
> > +
> > +Example:
> > +
> > +#include <dt-bindings/dma/nbpfaxi.h>
> > +
> > +...
> > +               dmas = <&dma 0 (NBPF_SLAVE_RQ_HIGH | NBPF_SLAVE_RQ_LEVEL)
> > +                       &dma 1 (NBPF_SLAVE_RQ_HIGH | NBPF_SLAVE_RQ_LEVEL)>;
> > +               dma-names = "rx", "tx";
> > diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> > index ba06d1d..513207a 100644
> > --- a/drivers/dma/Kconfig
> > +++ b/drivers/dma/Kconfig
> > @@ -361,6 +361,12 @@ config FSL_EDMA
> >           multiplexing capability for DMA request sources(slot).
> >           This module can be found on Freescale Vybrid and LS-1 SoCs.
> >  
> > +config NBPFAXI_DMA
> > +       tristate "Renesas Type-AXI NBPF DMA support"
> > +       select DMA_ENGINE
> > +       help
> > +         Support for "Type-AXI" NBPF DMA IPs from Renesas
> > +
> >  config DMA_ENGINE
> >         bool
> >  
> > diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
> > index 5150c82..9589ebb 100644
> > --- a/drivers/dma/Makefile
> > +++ b/drivers/dma/Makefile
> > @@ -46,3 +46,4 @@ obj-$(CONFIG_K3_DMA) += k3dma.o
> >  obj-$(CONFIG_MOXART_DMA) += moxart-dma.o
> >  obj-$(CONFIG_FSL_EDMA) += fsl-edma.o
> >  obj-$(CONFIG_QCOM_BAM_DMA) += qcom_bam_dma.o
> > +obj-$(CONFIG_NBPFAXI_DMA) += nbpfaxi.o
> > diff --git a/drivers/dma/nbpfaxi.c b/drivers/dma/nbpfaxi.c
> > new file mode 100644
> > index 0000000..152bb13
> > --- /dev/null
> > +++ b/drivers/dma/nbpfaxi.c
> > @@ -0,0 +1,1554 @@
> > +/*
> > + * Copyright (C) 2013-2014 Renesas Europe Ltd.
> > + * Author: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of version 2 of the GNU General Public License as
> > + * published by the Free Software Foundation.
> > + */
> > +
> > +#include <linux/bitmap.h>
> > +#include <linux/bitops.h>
> > +#include <linux/clk.h>
> > +#include <linux/dma-mapping.h>
> > +#include <linux/dmaengine.h>
> > +#include <linux/err.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/io.h>
> > +#include <linux/log2.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/of_device.h>
> > +#include <linux/of_dma.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/slab.h>
> > +
> > +#include <dt-bindings/dma/nbpfaxi.h>
> > +
> > +#include "dmaengine.h"
> > +
> > +#define NBPF_REG_CHAN_OFFSET   0
> > +#define NBPF_REG_CHAN_SIZE     0x40
> > +
> > +/* Channel Current Transaction Byte register */
> > +#define NBPF_CHAN_CUR_TR_BYTE  0x20
> > +
> > +/* Channel Status register */
> > +#define NBPF_CHAN_STAT 0x24
> > +#define NBPF_CHAN_STAT_EN      1
> > +#define NBPF_CHAN_STAT_TACT    4
> > +#define NBPF_CHAN_STAT_ERR     0x10
> > +#define NBPF_CHAN_STAT_END     0x20
> > +#define NBPF_CHAN_STAT_TC      0x40
> > +#define NBPF_CHAN_STAT_DER     0x400
> > +
> > +/* Channel Control register */
> > +#define NBPF_CHAN_CTRL 0x28
> > +#define NBPF_CHAN_CTRL_SETEN   1
> > +#define NBPF_CHAN_CTRL_CLREN   2
> > +#define NBPF_CHAN_CTRL_STG     4
> > +#define NBPF_CHAN_CTRL_SWRST   8
> > +#define NBPF_CHAN_CTRL_CLRRQ   0x10
> > +#define NBPF_CHAN_CTRL_CLREND  0x20
> > +#define NBPF_CHAN_CTRL_CLRTC   0x40
> > +#define NBPF_CHAN_CTRL_SETSUS  0x100
> > +#define NBPF_CHAN_CTRL_CLRSUS  0x200
> > +
> > +/* Channel Configuration register */
> > +#define NBPF_CHAN_CFG  0x2c
> > +#define NBPF_CHAN_CFG_SEL      7               /* terminal SELect: 0..7 */
> > +#define NBPF_CHAN_CFG_REQD     8               /* REQuest Direction: DMAREQ is 0: input, 1: output */
> > +#define NBPF_CHAN_CFG_LOEN     0x10            /* LOw ENable: low DMA request line is: 0: inactive, 1: active */
> > +#define NBPF_CHAN_CFG_HIEN     0x20            /* HIgh ENable: high DMA request line is: 0: inactive, 1: active */
> > +#define NBPF_CHAN_CFG_LVL      0x40            /* LeVeL: DMA request line is sensed as 0: edge, 1: level */
> > +#define NBPF_CHAN_CFG_AM       0x700           /* ACK Mode: 0: Pulse mode, 1: Level mode, b'1x: Bus Cycle */
> > +#define NBPF_CHAN_CFG_SDS      0xf000          /* Source Data Size: 0: 8 bits,... , 7: 1024 bits */
> > +#define NBPF_CHAN_CFG_DDS      0xf0000         /* Destination Data Size: as above */
> > +#define NBPF_CHAN_CFG_SAD      0x100000        /* Source ADdress counting: 0: increment, 1: fixed */
> > +#define NBPF_CHAN_CFG_DAD      0x200000        /* Destination ADdress counting: 0: increment, 1: fixed */
> > +#define NBPF_CHAN_CFG_TM       0x400000        /* Transfer Mode: 0: single, 1: block TM */
> > +#define NBPF_CHAN_CFG_DEM      0x1000000       /* DMAEND interrupt Mask */
> > +#define NBPF_CHAN_CFG_TCM      0x2000000       /* DMATCO interrupt Mask */
> > +#define NBPF_CHAN_CFG_SBE      0x8000000       /* Sweep Buffer Enable */
> > +#define NBPF_CHAN_CFG_RSEL     0x10000000      /* RM: Register Set sELect */
> > +#define NBPF_CHAN_CFG_RSW      0x20000000      /* RM: Register Select sWitch */
> > +#define NBPF_CHAN_CFG_REN      0x40000000      /* RM: Register Set Enable */
> > +#define NBPF_CHAN_CFG_DMS      0x80000000      /* 0: register mode (RM), 1: link mode (LM) */
> > +
> > +#define NBPF_CHAN_NXLA 0x38
> > +#define NBPF_CHAN_CRLA 0x3c
> > +
> > +/* Link Header field */
> > +#define NBPF_HEADER_LV 1
> > +#define NBPF_HEADER_LE 2
> > +#define NBPF_HEADER_WBD        4
> > +#define NBPF_HEADER_DIM        8
> > +
> > +#define NBPF_CTRL      0x300
> > +#define NBPF_CTRL_PR   1               /* 0: fixed priority, 1: round robin */
> > +#define NBPF_CTRL_LVINT        2               /* DMAEND and DMAERR signalling: 0: pulse, 1: level */
> > +
> > +#define NBPF_DSTAT_ER  0x314
> > +#define NBPF_DSTAT_END 0x318
> > +
> > +#define NBPF_DMA_BUSWIDTHS \
> > +       (BIT(DMA_SLAVE_BUSWIDTH_UNDEFINED) | \
> > +        BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) | \
> > +        BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) | \
> > +        BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) | \
> > +        BIT(DMA_SLAVE_BUSWIDTH_8_BYTES))
> > +
> > +struct nbpf_config {
> > +       int num_channels;
> > +       int buffer_size;
> > +};
> > +
> > +/*
> > + * We've got 3 types of objects, used to describe DMA transfers:
> > + * 1. high-level descriptor, containing a struct dma_async_tx_descriptor object
> > + *     in it, used to communicate with the user
> > + * 2. hardware DMA link descriptors, that we pass to DMAC for DMA transfer
> > + *     queuing, these must be DMAable, using either the streaming DMA API or
> > + *     allocated from coherent memory - one per SG segment
> > + * 3. one per SG segment descriptors, used to manage HW link descriptors from
> > + *     (2). They do not have to be DMAable. They can either be (a) allocated
> > + *     together with link descriptors as mixed (DMA / CPU) objects, or (b)
> > + *     separately. Even if allocated separately it would be best to link them
> > + *     to link descriptors once during channel resource allocation and always
> > + *     use them as a single object.
> > + * Therefore for both cases (a) and (b) at run-time objects (2) and (3) shall be
> > + * treated as a single SG segment descriptor.
> > + */
> > +
> > +struct nbpf_link_reg {
> > +       u32     header;
> > +       u32     src_addr;
> > +       u32     dst_addr;
> > +       u32     transaction_size;
> > +       u32     config;
> > +       u32     interval;
> > +       u32     extension;
> > +       u32     next;
> > +} __packed;
> > +
> > +struct nbpf_device;
> > +struct nbpf_channel;
> > +struct nbpf_desc;
> > +
> > +struct nbpf_link_desc {
> > +       struct nbpf_link_reg *hwdesc;
> > +       dma_addr_t hwdesc_dma_addr;
> 
> Are you sure about this? IIUC this is about what hardware has.
> dma_addr_t is variable_sized type. If it's correct, then you have to use
> %pad in printk's across your code.
> 
> Otherwise use static length types like u32.

It's used to store a return value of dma_map_single() and as an argument 
to dma_sync_single_for_device() and dma_unmap_single(). and it's also used 
to write to the hardware. So, I think it's better to keep the current 
type, but to add explicit casts, where it goes to hardware and use 
appropriate printk() formats, as you're suggesting.

> > +       struct nbpf_desc *desc;
> > +       struct list_head node;
> > +};
> > +
> > +/**
> > + * @sg:                list of hardware descriptors, represented by struct nbpf_link_desc
> > + * @node:      member in channel descriptor lists
> > + */
> > +struct nbpf_desc {
> > +       struct dma_async_tx_descriptor async_tx;
> > +       bool user_wait;
> > +       struct nbpf_channel *chan;
> > +       struct list_head sg;
> > +       struct list_head node;
> > +};
> > +
> > +/* Take a wild guess: allocate 4 segments per descriptor */
> > +#define NBPF_SEGMENTS_PER_DESC 4
> > +#define NBPF_DESCS_PER_PAGE ((PAGE_SIZE - sizeof(struct list_head)) /  \
> > +       (sizeof(struct nbpf_desc) +                                     \
> > +        NBPF_SEGMENTS_PER_DESC *                                       \
> > +        (sizeof(struct nbpf_link_desc) + sizeof(struct nbpf_link_reg))))
> > +#define NBPF_SEGMENTS_PER_PAGE (NBPF_SEGMENTS_PER_DESC * NBPF_DESCS_PER_PAGE)
> > +
> > +struct nbpf_desc_page {
> > +       struct list_head node;
> > +       struct nbpf_desc desc[NBPF_DESCS_PER_PAGE];
> > +       struct nbpf_link_desc ldesc[NBPF_SEGMENTS_PER_PAGE];
> > +       struct nbpf_link_reg hwdesc[NBPF_SEGMENTS_PER_PAGE];
> > +};
> > +
> > +#define NBPF_STATUS_SHIFT 7
> > +#define NBPF_STATUS_KEEP BIT(NBPF_STATUS_SHIFT)
> > +#define NBPF_STATUS_MASK (NBPF_STATUS_KEEP - 1)
> > +
> > +/**
> > + * struct nbpf_channel - one DMAC channel
> > + * @dma_chan:  standard dmaengine channel object
> > + * @base:      register address base
> > + * @nbpf:      DMAC
> > + * @name:      IRQ name
> > + * @irq:       IRQ number
> > + * @slave_addr:        address for slave DMA
> > + * @slave_width:slave data size in bytes
> > + * @slave_burst:maximum slave burst size in bytes
> > + * @terminal:  DMA terminal, assigned to this channel
> > + * @dmarq_cfg: DMA request line configuration - high / low, edge / level for NBPF_CHAN_CFG
> > + * @flags:     configuration flags from DT
> > + * @lock:      protect descriptor lists
> > + * @free_links:        list of free link descriptors
> > + * @free:      list of free descriptors
> > + * @queued:    list of queued descriptors
> > + * @active:    list of descriptors, scheduled for processing
> > + * @done:      list of completed descriptors, waiting post-processing
> > + * @desc_page: list of additionally allocated descriptor pages - if any
> > + */
> > +struct nbpf_channel {
> > +       struct dma_chan dma_chan;
> > +       void __iomem *base;
> > +       struct nbpf_device *nbpf;
> > +       char name[16];
> > +       int irq;
> > +       dma_addr_t slave_addr;
> > +       u32 slave_width;
> > +       u32 slave_burst;
> > +       unsigned int terminal;
> > +       u32 dmarq_cfg;
> > +       unsigned long flags;
> > +       spinlock_t lock;
> > +       struct list_head free_links;
> > +       struct list_head free;
> > +       struct list_head queued;
> > +       struct list_head active;
> > +       struct list_head done;
> > +       struct list_head desc_page;
> > +       struct nbpf_desc *running;
> > +       dma_cookie_t cookie_forgotten;
> > +       DECLARE_BITMAP(status, NBPF_STATUS_KEEP);
> > +       bool paused;
> > +};
> > +
> > +struct nbpf_device {
> > +       struct dma_device dma_dev;
> > +       void __iomem *base;
> > +       struct clk *clk;
> > +       const struct nbpf_config *config;
> > +       struct nbpf_channel chan[];
> > +};
> > +
> > +enum nbpf_model {
> > +       NBPF1B4,
> > +       NBPF1B8,
> > +       NBPF1B16,
> > +       NBPF4B4,
> > +       NBPF4B8,
> > +       NBPF4B16,
> > +       NBPF8B4,
> > +       NBPF8B8,
> > +       NBPF8B16,
> > +};
> > +
> > +static struct nbpf_config nbpf_cfg[] = {
> > +       [NBPF1B4] = {
> > +               .num_channels = 1,
> > +               .buffer_size = 4,
> > +       },
> > +       [NBPF1B8] = {
> > +               .num_channels = 1,
> > +               .buffer_size = 8,
> > +       },
> > +       [NBPF1B16] = {
> > +               .num_channels = 1,
> > +               .buffer_size = 16,
> > +       },
> > +       [NBPF4B4] = {
> > +               .num_channels = 4,
> > +               .buffer_size = 4,
> > +       },
> > +       [NBPF4B8] = {
> > +               .num_channels = 4,
> > +               .buffer_size = 8,
> > +       },
> > +       [NBPF4B16] = {
> > +               .num_channels = 4,
> > +               .buffer_size = 16,
> > +       },
> > +       [NBPF8B4] = {
> > +               .num_channels = 8,
> > +               .buffer_size = 4,
> > +       },
> > +       [NBPF8B8] = {
> > +               .num_channels = 8,
> > +               .buffer_size = 8,
> > +       },
> > +       [NBPF8B16] = {
> > +               .num_channels = 8,
> > +               .buffer_size = 16,
> > +       },
> > +};
> > +
> > +#define nbpf_to_chan(d) container_of(d, struct nbpf_channel, dma_chan)
> > +
> > +/*
> > + * dmaengine drivers seem to have a lot in common and instead of sharing more
> > + * code, they reimplement those common algorithms independently. In this driver
> > + * we try to separate the hardware-specific part from the (largely) generic
> > + * part. This improves code readability and makes it possible in the future to
> > + * reuse the generic code in form of a helper library. That generic code should
> > + * be suitable for various DMA controllers, using transfer descriptors in RAM
> > + * and pushing one SG list at a time to the DMA controller.
> > + */
> > +
> > +/*             Hardware-specific part          */
> > +
> > +static inline u32 nbpf_chan_read(struct nbpf_channel *chan,
> > +                                unsigned int offset)
> > +{
> > +       u32 data = ioread32(chan->base + offset);
> > +       pr_debug("%s(0x%p + 0x%x) = 0x%x\n", __func__, chan->base, offset, data);
> 
> Could you use dev_vdbg() for those prints?

Ok

> > +       return data;
> > +}
> > +
> > +static inline void nbpf_chan_write(struct nbpf_channel *chan,
> > +                                  unsigned int offset, u32 data)
> > +{
> > +       iowrite32(data, chan->base + offset);
> > +       pr_debug("%s(0x%p + 0x%x) = 0x%x\n", __func__, chan->base, offset, data);
> > +}
> > +
> > +static inline u32 nbpf_read(struct nbpf_device *nbpf,
> > +                           unsigned int offset)
> > +{
> > +       u32 data = ioread32(nbpf->base + offset);
> > +       pr_debug("%s(0x%p + 0x%x) = 0x%x\n", __func__, nbpf->base, offset, data);
> > +       return data;
> > +}
> > +
> > +static inline void nbpf_write(struct nbpf_device *nbpf,
> > +                             unsigned int offset, u32 data)
> > +{
> > +       iowrite32(data, nbpf->base + offset);
> > +       pr_debug("%s(0x%p + 0x%x) = 0x%x\n", __func__, nbpf->base, offset, data);
> > +}
> > +
> > +static void nbpf_chan_halt(struct nbpf_channel *chan)
> > +{
> > +       nbpf_chan_write(chan, NBPF_CHAN_CTRL, NBPF_CHAN_CTRL_CLREN);
> > +}
> > +
> > +static bool nbpf_status_get(struct nbpf_channel *chan)
> > +{
> > +       u32 status = nbpf_read(chan->nbpf, NBPF_DSTAT_END);
> > +
> > +       return status & BIT(chan - chan->nbpf->chan);
> > +}
> > +
> > +static void nbpf_status_ack(struct nbpf_channel *chan)
> > +{
> > +       nbpf_chan_write(chan, NBPF_CHAN_CTRL, NBPF_CHAN_CTRL_CLREND);
> > +}
> > +
> > +static u32 nbpf_error_get(struct nbpf_device *nbpf)
> > +{
> > +       return nbpf_read(nbpf, NBPF_DSTAT_ER);
> > +}
> > +
> > +struct nbpf_channel *nbpf_error_get_channel(struct nbpf_device *nbpf, u32 error)
> > +{
> > +       return nbpf->chan + __ffs(error);
> > +}
> > +
> > +static void nbpf_error_clear(struct nbpf_channel *chan)
> > +{
> > +       u32 status;
> > +       int i;
> > +
> > +       /* stop the channel, make sure DMA has been aborted */
> 
> Maybe first letter capital?

Sure :)

> > +       nbpf_chan_halt(chan);
> > +
> > +       for (i = 0; i < 1000; i++) {
> > +               status = nbpf_chan_read(chan, NBPF_CHAN_STAT);
> > +               if (!(status & NBPF_CHAN_STAT_TACT))
> > +                       break;
> > +               cpu_relax();
> > +       }
> > +
> > +       if (i == 1000)
> > +               dev_err(chan->dma_chan.device->dev, "%s() abort timeout\n", __func__);
> 
> You may simplify this stub by using countdown while loop. Like
> 
> int i = 1000;
> 
> while (--i && read() & CUSTOM_BIT)
>  cpu_relax();
> 
> if (!i)
>  "timeout";

Well, I'll make it a countdown loop, just to replace "i < 1000" with "i" 
and "i == 1000" with "!i" which do look a bit nicer. But I'll keep the 
"status" variable and to justify it I'll pring it out in the error 
message.

> > +
> > +       nbpf_chan_write(chan, NBPF_CHAN_CTRL, NBPF_CHAN_CTRL_SWRST);
> > +}
> > +
> > +static int nbpf_start(struct nbpf_desc *desc)
> > +{
> > +       struct nbpf_channel *chan = desc->chan;
> > +       struct nbpf_link_desc *ldesc = list_first_entry(&desc->sg, struct nbpf_link_desc, node);
> > +
> > +       nbpf_chan_write(chan, NBPF_CHAN_NXLA, ldesc->hwdesc_dma_addr);
> > +       nbpf_chan_write(chan, NBPF_CHAN_CTRL, NBPF_CHAN_CTRL_SETEN | NBPF_CHAN_CTRL_CLRSUS);
> > +       chan->paused = false;
> > +
> > +       /* Software trigger MEMCPY - only MEMCPY uses the block mode */
> > +       if (ldesc->hwdesc->config & NBPF_CHAN_CFG_TM)
> > +               nbpf_chan_write(chan, NBPF_CHAN_CTRL, NBPF_CHAN_CTRL_STG);
> > +
> > +       dev_dbg(chan->nbpf->dma_dev.dev, "%s(): next 0x%x, cur 0x%x\n", __func__,
> > +               nbpf_chan_read(chan, NBPF_CHAN_NXLA), nbpf_chan_read(chan, NBPF_CHAN_CRLA));
> > +
> > +       return 0;
> > +}
> > +
> > +static void nbpf_chan_prepare(struct nbpf_channel *chan)
> > +{
> > +       chan->dmarq_cfg = (chan->flags & NBPF_SLAVE_RQ_HIGH ? NBPF_CHAN_CFG_HIEN : 0) |
> > +               (chan->flags & NBPF_SLAVE_RQ_LOW ? NBPF_CHAN_CFG_LOEN : 0) |
> > +               (chan->flags & NBPF_SLAVE_RQ_LEVEL ?
> > +                NBPF_CHAN_CFG_LVL | (NBPF_CHAN_CFG_AM & 0x200) : 0) |
> > +               chan->terminal;
> > +}
> > +
> > +static void nbpf_chan_prepare_default(struct nbpf_channel *chan)
> > +{
> > +       /* Don't output DMAACK */
> > +       chan->dmarq_cfg = NBPF_CHAN_CFG_AM & 0x400;
> > +       chan->terminal = 0;
> > +       chan->flags = 0;
> > +}
> > +
> > +static void nbpf_chan_configure(struct nbpf_channel *chan)
> > +{
> > +       /*
> > +        * We assume, that only the link mode and DMA request line configuration
> > +        * have to be set in the configuration register manually. Dynamic
> > +        * per-transfer configuration will be loaded from transfer descriptors.
> > +        */
> > +       nbpf_chan_write(chan, NBPF_CHAN_CFG, NBPF_CHAN_CFG_DMS | chan->dmarq_cfg);
> > +}
> > +
> > +static u32 nbpf_xfer_ds(struct nbpf_device *nbpf, size_t size)
> > +{
> > +       /* Maximum supported bursts depend on the buffer size */
> > +       return min_t(int, __ffs(size), ilog2(nbpf->config->buffer_size * 8));
> > +}
> > +
> > +static u32 nbpf_xfer_size(struct nbpf_device *nbpf,
> > +                         enum dma_slave_buswidth width, u32 burst)
> > +{
> > +       size_t size;
> > +
> > +       if (!burst)
> > +               burst = 1;
> > +
> > +       switch (width) {
> > +       case DMA_SLAVE_BUSWIDTH_8_BYTES:
> > +               size = 8 * burst;
> > +               break;
> > +       case DMA_SLAVE_BUSWIDTH_4_BYTES:
> > +               size = 4 * burst;
> > +               break;
> > +       case DMA_SLAVE_BUSWIDTH_2_BYTES:
> > +               size = 2 * burst;
> > +               break;
> > +       default:
> > +               pr_warn("%s(): invalid bus width %u\n", __func__, width);
> > +       case DMA_SLAVE_BUSWIDTH_1_BYTE:
> > +               size = burst;
> > +       }
> > +
> > +       return nbpf_xfer_ds(nbpf, size);
> > +}
> > +
> > +/*
> > + * We need a way to recognise slaves, whose data is sent "raw" over the bus,
> > + * i.e. it isn't known in advance how many bytes will be received. Therefore
> > + * the slave driver has to provide a "large enough" buffer and either read the
> > + * buffer, when it is full, or detect, that some data has arrived, then wait for
> > + * a timeout, if no more data arrives - receive what's already there. We want to
> > + * handle such slaves in a special way to allow an optimised mode for other
> > + * users, for whom the amount of data is known in advance. So far there's no way
> > + * to recognise such slaves. We use a data-width check to distinguish between
> > + * the SD host and the PL011 UART.
> > + */
> > +#define nbpf_slave_can_burst(chan) (chan->slave_width >= 3)
> > +
> > +static int nbpf_prep_one(struct nbpf_link_desc *ldesc,
> > +                        enum dma_transfer_direction direction,
> > +                        dma_addr_t src, dma_addr_t dst, size_t size, bool last)
> > +{
> > +       struct nbpf_link_reg *hwdesc = ldesc->hwdesc;
> > +       struct nbpf_desc *desc = ldesc->desc;
> > +       struct nbpf_channel *chan = desc->chan;
> > +       struct device *dev = chan->dma_chan.device->dev;
> > +       size_t mem_xfer, slave_xfer;
> > +
> > +       hwdesc->header = NBPF_HEADER_WBD | NBPF_HEADER_LV |
> > +               (last ? NBPF_HEADER_LE : 0);
> > +
> > +       hwdesc->src_addr = src;
> > +       hwdesc->dst_addr = dst;
> > +       hwdesc->transaction_size = size;
> > +
> > +       /*
> > +        * set config: SAD, DAD, DDS, SDS, etc.
> > +        * Note on transfer sizes: the DMAC can perform unaligned DMA transfers,
> > +        * but it is important to have transaction size a multiple of both
> > +        * receiver and transmitter transfer sizes. It is also possible to use
> > +        * different RAM and device transfer sizes, and it does work well with
> > +        * some devices, e.g. with V08R07S01E SD host controllers, which can use
> > +        * 128 byte transfers. But this doesn't work with other devices,
> > +        * especially when the transaction size is unknown. This is the case,
> > +        * e.g. with serial drivers like amba-pl011.c. For reception it sets up
> > +        * the transaction size of 4K and if fewer bytes are received, it
> > +        * pauses DMA and reads out data received via DMA as well as those left
> > +        * in the Rx FIFO. For this to work with the RAM side using burst
> > +        * transfers we enable the SBE bit and terminate the transfer in our
> > +        * DMA_PAUSE handler.
> > +        */
> > +       mem_xfer = nbpf_xfer_ds(chan->nbpf, size);
> > +       slave_xfer = min(mem_xfer, nbpf_slave_can_burst(chan) ?
> > +                        chan->slave_burst : chan->slave_width);
> 
> min_t?

The compiler didn't complain, but it might, if size_t isn't compatible 
with u32 on some arches, so, I changed .slave_burst and .slave_width to 
size_t too.

> > +
> > +       switch (direction) {
> > +       case DMA_DEV_TO_MEM:
> > +               /*
> > +                * Is the slave narrower than 64 bits, i.e. isn't using the full
> > +                * bus width and cannot use bursts?
> > +                */
> > +               if (mem_xfer > chan->slave_burst && !nbpf_slave_can_burst(chan))
> > +                       mem_xfer = chan->slave_burst;
> > +               /* Device-to-RAM DMA is unreliable without REQD set */
> > +               hwdesc->config = NBPF_CHAN_CFG_SAD | (NBPF_CHAN_CFG_DDS & (mem_xfer << 16)) |
> > +                       (NBPF_CHAN_CFG_SDS & (slave_xfer << 12)) | NBPF_CHAN_CFG_REQD |
> > +                       NBPF_CHAN_CFG_SBE;
> > +               break;
> > +       case DMA_MEM_TO_DEV:
> > +               hwdesc->config = NBPF_CHAN_CFG_DAD | (NBPF_CHAN_CFG_SDS & (mem_xfer << 12)) |
> > +                       (NBPF_CHAN_CFG_DDS & (slave_xfer << 16)) | NBPF_CHAN_CFG_REQD;
> > +               break;
> > +       case DMA_MEM_TO_MEM:
> > +               hwdesc->config = NBPF_CHAN_CFG_TCM | NBPF_CHAN_CFG_TM |
> > +                       (NBPF_CHAN_CFG_SDS & (mem_xfer << 12)) |
> > +                       (NBPF_CHAN_CFG_DDS & (mem_xfer << 16));
> > +               break;
> > +       default:
> > +               return -EINVAL;
> > +       }
> > +
> > +       hwdesc->config |= chan->dmarq_cfg | (last ? 0 : NBPF_CHAN_CFG_DEM) |
> > +               NBPF_CHAN_CFG_DMS;
> > +
> > +       dev_dbg(dev, "%s(): desc @ 0x%x: hdr 0x%x, cfg 0x%x, %u @ 0x%x -> 0x%x\n",
> 
> %pad for src and dst, please.

Ok

> > +               __func__, ldesc->hwdesc_dma_addr, hwdesc->header,
> > +               hwdesc->config, size, src, dst);
> > +
> > +       dma_sync_single_for_device(dev, ldesc->hwdesc_dma_addr, sizeof(*hwdesc),
> > +                                  DMA_TO_DEVICE);
> > +
> > +       return 0;
> > +}
> > +
> > +static size_t nbpf_bytes_left(struct nbpf_channel *chan)
> > +{
> > +       return nbpf_chan_read(chan, NBPF_CHAN_CUR_TR_BYTE);
> > +}
> > +
> > +static void nbpf_configure(struct nbpf_device *nbpf)
> > +{
> > +       nbpf_write(nbpf, NBPF_CTRL, NBPF_CTRL_LVINT);
> > +}
> > +
> > +static void nbpf_pause(struct nbpf_channel *chan)
> > +{
> > +       nbpf_chan_write(chan, NBPF_CHAN_CTRL, NBPF_CHAN_CTRL_SETSUS);
> > +       /* See comment in nbpf_prep_one() */
> > +       nbpf_chan_write(chan, NBPF_CHAN_CTRL, NBPF_CHAN_CTRL_CLREN);
> > +}
> > +
> > +/*             Generic part                    */
> > +
> > +/* DMA ENGINE functions */
> > +static void nbpf_issue_pending(struct dma_chan *dchan)
> > +{
> > +       struct nbpf_channel *chan = nbpf_to_chan(dchan);
> > +       unsigned long flags;
> > +
> > +       dev_dbg(dchan->device->dev, "Entry %s()\n", __func__);
> > +
> > +       spin_lock_irqsave(&chan->lock, flags);
> > +       if (list_empty(&chan->queued))
> > +               goto unlock;
> > +
> > +       list_splice_tail_init(&chan->queued, &chan->active);
> > +
> > +       if (!chan->running) {
> > +               struct nbpf_desc *desc = list_first_entry(&chan->active,
> > +                                               struct nbpf_desc, node);
> > +               if (!nbpf_start(desc))
> > +                       chan->running = desc;
> > +       }
> > +
> > +unlock:
> > +       spin_unlock_irqrestore(&chan->lock, flags);
> > +}
> > +
> > +/*
> > + * cookies are numbered 1...DMA_MAX_COOKIE=INT_MAX
> > + */
> > +static void nbpf_cookie_update(struct nbpf_channel *chan, dma_cookie_t cookie)
> > +{
> > +       dma_cookie_t forgotten = cookie - NBPF_STATUS_KEEP;
> > +
> > +       if (cookie < NBPF_STATUS_KEEP && !chan->cookie_forgotten)
> > +               /* Not forgetting yet */
> > +               return;
> > +
> > +       if (forgotten < DMA_MIN_COOKIE)
> > +               /* Wrapped */
> > +               forgotten = (DMA_MAX_COOKIE & ~NBPF_STATUS_MASK) + cookie;
> > +       chan->cookie_forgotten = forgotten;
> > +}
> > +
> > +static bool nbpf_cookie_in_cache(struct nbpf_channel *chan,
> > +               dma_cookie_t cookie, struct dma_tx_state *state)
> > +{
> > +       if (cookie > chan->cookie_forgotten)
> > +               return true;
> > +
> > +       /*
> > +        * We still remember the cookie, if it has wrapped beyond INT_MAX:
> > +        * (1) forgotten is almost INT_MAX
> > +        * cookie_forgotten >> NBPF_STATUS_SHIFT == DMA_MAX_COOKIE >> NBPF_STATUS_SHIFT
> > +        * and enquired is small
> > +        * (2)
> > +        * cookie & ~NBPF_STATUS_MASK == 0
> > +        */
> > +
> > +       return chan->cookie_forgotten >> NBPF_STATUS_SHIFT ==
> > +               DMA_MAX_COOKIE >> NBPF_STATUS_SHIFT &&
> > +               !(cookie < ~NBPF_STATUS_MASK);
> > +}
> > +
> > +static void nbpf_cookie_success(struct nbpf_channel *chan, dma_cookie_t cookie)
> > +{
> > +       nbpf_cookie_update(chan, cookie);
> > +       clear_bit(cookie & NBPF_STATUS_MASK, chan->status);
> > +}
> > +
> > +static void nbpf_cookie_fail(struct nbpf_channel *chan, dma_cookie_t cookie)
> > +{
> > +       nbpf_cookie_update(chan, cookie);
> > +       set_bit(cookie & NBPF_STATUS_MASK, chan->status);
> > +}
> > +
> > +static enum dma_status nbpf_cookie_cached(struct nbpf_channel *chan,
> > +               dma_cookie_t cookie, struct dma_tx_state *state)
> > +{
> > +       return test_bit(cookie & NBPF_STATUS_MASK, chan->status) ?
> > +               DMA_ERROR : DMA_COMPLETE;
> > +}
> > +
> > +static enum dma_status nbpf_tx_status(struct dma_chan *dchan,
> > +               dma_cookie_t cookie, struct dma_tx_state *state)
> > +{
> > +       struct nbpf_channel *chan = nbpf_to_chan(dchan);
> > +       enum dma_status status = dma_cookie_status(dchan, cookie, state);
> > +       dma_cookie_t running = chan->running ? chan->running->async_tx.cookie : -EINVAL;
> > +
> > +       if (chan->paused)
> > +               status = DMA_PAUSED;
> > +
> > +       /* Note: we cannot return residues for old cookies */
> > +       if (state && cookie == running) {
> > +               state->residue = nbpf_bytes_left(chan);
> > +               dev_dbg(dchan->device->dev, "%s(): residue %u\n", __func__,
> > +                       state->residue);
> > +       }
> > +
> > +       if (status == DMA_IN_PROGRESS || status == DMA_PAUSED)
> > +               return status;
> > +
> > +       if (nbpf_cookie_in_cache(chan, cookie, state))
> > +               return nbpf_cookie_cached(chan, cookie, state);
> > +
> > +       return status;
> > +}
> > +
> > +static dma_cookie_t nbpf_tx_submit(struct dma_async_tx_descriptor *tx)
> > +{
> > +       struct nbpf_desc *desc = container_of(tx, struct nbpf_desc, async_tx);
> > +       struct nbpf_channel *chan = desc->chan;
> > +       unsigned long flags;
> > +       dma_cookie_t cookie;
> > +
> > +       spin_lock_irqsave(&chan->lock, flags);
> > +       cookie = dma_cookie_assign(tx);
> > +       list_add_tail(&desc->node, &chan->queued);
> > +       spin_unlock_irqrestore(&chan->lock, flags);
> > +
> > +       dev_dbg(chan->dma_chan.device->dev, "Entry %s(%d)\n", __func__, cookie);
> > +
> > +       return cookie;
> > +}
> > +
> > +static int nbpf_desc_page_alloc(struct nbpf_channel *chan)
> > +{
> > +       struct dma_chan *dchan = &chan->dma_chan;
> > +       struct nbpf_desc_page *dpage = (void *)get_zeroed_page(GFP_KERNEL | GFP_DMA);
> > +       struct nbpf_link_desc *ldesc;
> > +       struct nbpf_link_reg *hwdesc;
> > +       struct nbpf_desc *desc;
> > +       LIST_HEAD(head);
> > +       LIST_HEAD(lhead);
> > +       int i;
> > +       struct device *dev = dchan->device->dev;
> > +
> > +       if (!dpage)
> > +               return -ENOMEM;
> > +
> > +       dev_dbg(dev, "%s(): alloc %lu descriptors, %lu segments, total alloc %u\n",
> > +               __func__, NBPF_DESCS_PER_PAGE, NBPF_SEGMENTS_PER_PAGE, sizeof(*dpage));
> > +
> > +       for (i = 0, ldesc = dpage->ldesc, hwdesc = dpage->hwdesc;
> > +            i < ARRAY_SIZE(dpage->ldesc);
> > +            i++, ldesc++, hwdesc++) {
> > +               ldesc->hwdesc = hwdesc;
> > +               list_add_tail(&ldesc->node, &lhead);
> > +               ldesc->hwdesc_dma_addr = dma_map_single(dchan->device->dev,
> > +                                       hwdesc, sizeof(*hwdesc), DMA_TO_DEVICE);
> > +
> > +               dev_dbg(dev, "%s(): mapped %p to %u\n", __func__,
> > +                       hwdesc, ldesc->hwdesc_dma_addr);
> > +       }
> > +
> > +       for (i = 0, desc = dpage->desc;
> > +            i < ARRAY_SIZE(dpage->desc);
> > +            i++, desc++) {
> > +               dma_async_tx_descriptor_init(&desc->async_tx, dchan);
> > +               desc->async_tx.tx_submit = nbpf_tx_submit;
> > +               desc->chan = chan;
> > +               INIT_LIST_HEAD(&desc->sg);
> > +               list_add_tail(&desc->node, &head);
> > +       }
> > +
> > +       /*
> > +        * This function cannot be called from interrupt context, so, no need to
> > +        * save flags
> > +        */
> > +       spin_lock_irq(&chan->lock);
> > +       list_splice_tail(&lhead, &chan->free_links);
> > +       list_splice_tail(&head, &chan->free);
> > +       list_add(&dpage->node, &chan->desc_page);
> > +       spin_unlock_irq(&chan->lock);
> > +
> > +       return ARRAY_SIZE(dpage->desc);
> > +}
> > +
> > +static void nbpf_desc_put(struct nbpf_desc *desc)
> > +{
> > +       struct nbpf_channel *chan = desc->chan;
> > +       struct nbpf_link_desc *ldesc, *tmp;
> > +       unsigned long flags;
> > +
> > +       spin_lock_irqsave(&chan->lock, flags);
> > +       list_for_each_entry_safe(ldesc, tmp, &desc->sg, node)
> > +               list_move(&ldesc->node, &chan->free_links);
> > +
> > +       list_add(&desc->node, &chan->free);
> > +       spin_unlock_irqrestore(&chan->lock, flags);
> > +}
> > +
> > +static void nbpf_scan_acked(struct nbpf_channel *chan)
> > +{
> > +       struct nbpf_desc *desc, *tmp;
> > +       unsigned long flags;
> > +       LIST_HEAD(head);
> > +
> > +       spin_lock_irqsave(&chan->lock, flags);
> > +       list_for_each_entry_safe(desc, tmp, &chan->done, node)
> > +               if (async_tx_test_ack(&desc->async_tx) && desc->user_wait) {
> > +                       list_move(&desc->node, &head);
> > +                       desc->user_wait = false;
> > +               }
> > +       spin_unlock_irqrestore(&chan->lock, flags);
> > +
> > +       list_for_each_entry_safe(desc, tmp, &head, node) {
> > +               list_del(&desc->node);
> > +               nbpf_desc_put(desc);
> > +       }
> > +}
> > +
> > +/*
> > + * We have to allocate descriptors with the channel lock dropped. This means,
> > + * before we re-acquire the lock buffers can be taken already, so we have to
> > + * re-check after re-acquiring the lock and possibly retry, if buffers are gone
> > + * again.
> > + */
> > +static struct nbpf_desc *nbpf_desc_get(struct nbpf_channel *chan, size_t len)
> > +{
> > +       struct nbpf_desc *desc = NULL;
> > +       struct nbpf_link_desc *ldesc, *prev = NULL;
> > +
> > +       nbpf_scan_acked(chan);
> > +
> > +       spin_lock_irq(&chan->lock);
> > +
> > +       do {
> > +               int i = 0, ret;
> > +
> > +               if (list_empty(&chan->free)) {
> > +                       /* No more free descriptors */
> > +                       spin_unlock_irq(&chan->lock);
> > +                       ret = nbpf_desc_page_alloc(chan);
> > +                       if (ret < 0)
> > +                               return NULL;
> > +                       spin_lock_irq(&chan->lock);
> > +                       continue;
> > +               }
> > +               desc = list_first_entry(&chan->free, struct nbpf_desc, node);
> > +               list_del(&desc->node);
> > +
> > +               do {
> > +                       if (list_empty(&chan->free_links)) {
> > +                               /* No more free link descriptors */
> > +                               spin_unlock_irq(&chan->lock);
> > +                               ret = nbpf_desc_page_alloc(chan);
> > +                               if (ret < 0) {
> > +                                       nbpf_desc_put(desc);
> > +                                       return NULL;
> > +                               }
> > +                               spin_lock_irq(&chan->lock);
> > +                               continue;
> > +                       }
> > +
> > +                       ldesc = list_first_entry(&chan->free_links,
> > +                                                struct nbpf_link_desc, node);
> > +                       ldesc->desc = desc;
> > +                       if (prev)
> > +                               prev->hwdesc->next = ldesc->hwdesc_dma_addr;
> > +
> > +                       prev = ldesc;
> > +                       list_move_tail(&ldesc->node, &desc->sg);
> > +
> > +                       i++;
> > +               } while (i < len);
> > +       } while (!desc);
> > +
> > +       prev->hwdesc->next = 0;
> > +
> > +       spin_unlock_irq(&chan->lock);
> > +
> > +       return desc;
> > +}
> > +
> > +static void nbpf_chan_idle(struct nbpf_channel *chan)
> > +{
> > +       struct nbpf_desc *desc, *tmp;
> > +       unsigned long flags;
> > +       LIST_HEAD(head);
> > +
> > +       spin_lock_irqsave(&chan->lock, flags);
> > +
> > +       list_splice_init(&chan->done, &head);
> > +       list_splice_init(&chan->active, &head);
> > +       list_splice_init(&chan->queued, &head);
> > +
> > +       chan->running = NULL;
> > +
> > +       spin_unlock_irqrestore(&chan->lock, flags);
> > +
> > +       list_for_each_entry_safe(desc, tmp, &head, node) {
> > +               dev_dbg(chan->nbpf->dma_dev.dev, "%s(): force-free desc %p cookie %d\n",
> > +                       __func__, desc, desc->async_tx.cookie);
> > +               list_del(&desc->node);
> > +               nbpf_cookie_fail(chan, desc->async_tx.cookie);
> > +               nbpf_desc_put(desc);
> > +       }
> > +}
> > +
> > +static int nbpf_control(struct dma_chan *dchan, enum dma_ctrl_cmd cmd,
> > +                       unsigned long arg)
> > +{
> > +       struct nbpf_channel *chan = nbpf_to_chan(dchan);
> > +       struct dma_slave_config *config;
> > +
> > +       dev_dbg(dchan->device->dev, "Entry %s(%d)\n", __func__, cmd);
> > +
> > +       switch (cmd) {
> > +       case DMA_TERMINATE_ALL:
> > +               dev_dbg(dchan->device->dev, "Terminating\n");
> > +               nbpf_chan_halt(chan);
> > +               nbpf_chan_idle(chan);
> > +               break;
> > +       case DMA_SLAVE_CONFIG:
> > +               if (!arg)
> > +                       return -EINVAL;
> > +               config = (struct dma_slave_config *)arg;
> > +
> > +               /*
> > +                * We could check config->slave_id to match chan->terminal here,
> > +                * but with DT they would be coming from the same source, so
> > +                * such a check would be superflous
> > +                */
> > +
> > +               switch (config->direction) {
> > +               case DMA_MEM_TO_DEV:
> > +                       chan->slave_addr = config->dst_addr;
> > +                       chan->slave_width = nbpf_xfer_size(chan->nbpf,
> > +                                                       config->dst_addr_width, 1);
> > +                       chan->slave_burst = nbpf_xfer_size(chan->nbpf,
> > +                                                       config->dst_addr_width,
> > +                                                       config->dst_maxburst);
> > +                       break;
> > +               case DMA_DEV_TO_MEM:
> > +                       chan->slave_addr = config->src_addr;
> > +                       chan->slave_width = nbpf_xfer_size(chan->nbpf,
> > +                                                       config->src_addr_width, 1);
> > +                       chan->slave_burst = nbpf_xfer_size(chan->nbpf,
> > +                                                       config->src_addr_width,
> > +                                                       config->src_maxburst);
> > +                       break;
> > +               default:
> > +                       return -EINVAL;
> > +               }
> > +               break;
> > +       case DMA_PAUSE:
> > +               chan->paused = true;
> > +               nbpf_pause(chan);
> > +               break;
> > +       case DMA_RESUME:
> > +               /* Leave unimplemented until we get a use case. */
> > +       default:
> > +               return -ENXIO;
> > +       }
> > +
> > +       return 0;
> > +}
> > +
> > +static struct dma_async_tx_descriptor *nbpf_prep_sg(struct nbpf_channel *chan,
> > +               struct scatterlist *src_sg, struct scatterlist *dst_sg,
> > +               size_t len, enum dma_transfer_direction direction,
> > +               unsigned long flags)
> > +{
> > +       struct nbpf_link_desc *ldesc;
> > +       struct scatterlist *mem_sg;
> > +       struct nbpf_desc *desc;
> > +       bool inc_src, inc_dst;
> > +       int i = 0;
> > +
> > +       switch (direction) {
> > +       case DMA_DEV_TO_MEM:
> > +               mem_sg = dst_sg;
> > +               inc_src = false;
> > +               inc_dst = true;
> > +               break;
> > +       case DMA_MEM_TO_DEV:
> > +               mem_sg = src_sg;
> > +               inc_src = true;
> > +               inc_dst = false;
> > +               break;
> > +       default:
> > +       case DMA_MEM_TO_MEM:
> > +               mem_sg = src_sg;
> > +               inc_src = true;
> > +               inc_dst = true;
> > +       }
> > +
> > +       desc = nbpf_desc_get(chan, len);
> > +       if (!desc)
> > +               return NULL;
> > +
> > +       desc->async_tx.flags = flags;
> > +       desc->async_tx.cookie = -EBUSY;
> > +       desc->user_wait = false;
> > +
> > +       /*
> > +        * this is a private descriptor list, and we own the descriptor. No need
> 
> Capital letter first?

ok

> > +        * to lock.
> > +        */
> > +       list_for_each_entry(ldesc, &desc->sg, node) {
> > +               int ret = nbpf_prep_one(ldesc, direction,
> > +                                       sg_dma_address(src_sg),
> > +                                       sg_dma_address(dst_sg),
> > +                                       sg_dma_len(mem_sg),
> > +                                       i == len - 1);
> > +               if (ret < 0) {
> > +                       nbpf_desc_put(desc);
> > +                       return NULL;
> > +               }
> > +               if (inc_src)
> > +                       src_sg = sg_next(src_sg);
> > +               if (inc_dst)
> > +                       dst_sg = sg_next(dst_sg);
> > +               mem_sg = direction == DMA_DEV_TO_MEM ? dst_sg : src_sg;
> > +               i++;
> > +       }
> > +
> > +       /* The user has to return the descriptor to us ASAP via .tx_submit() */
> > +       return &desc->async_tx;
> > +}
> > +
> > +static struct dma_async_tx_descriptor *nbpf_prep_memcpy(
> > +       struct dma_chan *dchan, dma_addr_t dst, dma_addr_t src,
> > +       size_t len, unsigned long flags)
> > +{
> > +       struct nbpf_channel *chan = nbpf_to_chan(dchan);
> > +       struct scatterlist dst_sg;
> > +       struct scatterlist src_sg;
> > +
> > +       sg_init_table(&dst_sg, 1);
> > +       sg_init_table(&src_sg, 1);
> > +
> > +       sg_dma_address(&dst_sg) = dst;
> > +       sg_dma_address(&src_sg) = src;
> > +
> > +       sg_dma_len(&dst_sg) = len;
> > +       sg_dma_len(&src_sg) = len;
> > +
> > +       dev_dbg(dchan->device->dev, "%s(): %u @ 0x%x -> 0x%x\n",
> 
> %pad for dma_addr_t.

yep

> > +               __func__, len, src, dst);
> > +
> > +       return nbpf_prep_sg(chan, &src_sg, &dst_sg, 1,
> > +                           DMA_MEM_TO_MEM, flags);
> > +}
> > +
> > +static struct dma_async_tx_descriptor *nbpf_prep_memcpy_sg(
> > +       struct dma_chan *dchan,
> > +       struct scatterlist *dst_sg, unsigned int dst_nents,
> > +       struct scatterlist *src_sg, unsigned int src_nents,
> > +       unsigned long flags)
> > +{
> > +       struct nbpf_channel *chan = nbpf_to_chan(dchan);
> > +
> > +       if (dst_nents != src_nents)
> > +               return NULL;
> > +
> > +       return nbpf_prep_sg(chan, src_sg, dst_sg, src_nents,
> > +                           DMA_MEM_TO_MEM, flags);
> > +}
> > +
> > +static struct dma_async_tx_descriptor *nbpf_prep_slave_sg(
> > +       struct dma_chan *dchan, struct scatterlist *sgl, unsigned int sg_len,
> > +       enum dma_transfer_direction direction, unsigned long flags, void *context)
> > +{
> > +       struct nbpf_channel *chan = nbpf_to_chan(dchan);
> > +       struct scatterlist slave_sg;
> > +
> > +       dev_dbg(dchan->device->dev, "Entry %s()\n", __func__);
> > +
> > +       sg_init_table(&slave_sg, 1);
> > +       sg_dma_address(&slave_sg) = chan->slave_addr;
> > +
> > +       switch (direction) {
> > +       case DMA_MEM_TO_DEV:
> > +               return nbpf_prep_sg(chan, sgl, &slave_sg, sg_len,
> > +                                   direction, flags);
> > +       case DMA_DEV_TO_MEM:
> > +               return nbpf_prep_sg(chan, &slave_sg, sgl, sg_len,
> > +                                   direction, flags);
> > +       default:
> > +               return NULL;
> > +       }
> > +}
> > +
> > +static int nbpf_alloc_chan_resources(struct dma_chan *dchan)
> > +{
> > +       struct nbpf_channel *chan = nbpf_to_chan(dchan);
> > +       int ret;
> > +
> > +       INIT_LIST_HEAD(&chan->free);
> > +       INIT_LIST_HEAD(&chan->free_links);
> > +       INIT_LIST_HEAD(&chan->queued);
> > +       INIT_LIST_HEAD(&chan->active);
> > +       INIT_LIST_HEAD(&chan->done);
> > +
> > +       memset(chan->status, 0, sizeof(chan->status));
> > +
> > +       ret = nbpf_desc_page_alloc(chan);
> > +       if (ret < 0)
> > +               return ret;
> > +
> > +       dev_dbg(dchan->device->dev, "Entry %s(): terminal %u\n", __func__,
> > +               chan->terminal);
> > +
> > +       nbpf_chan_configure(chan);
> > +
> > +       return ret;
> > +}
> > +
> > +static void nbpf_free_chan_resources(struct dma_chan *dchan)
> > +{
> > +       struct nbpf_channel *chan = nbpf_to_chan(dchan);
> > +       struct nbpf_desc_page *dpage, *tmp;
> > +
> > +       dev_dbg(dchan->device->dev, "Entry %s()\n", __func__);
> > +
> > +       nbpf_chan_halt(chan);
> > +       /* Clean up for if a channel is re-used for MEMCPY after slave DMA */
> > +       nbpf_chan_prepare_default(chan);
> > +
> > +       list_for_each_entry_safe(dpage, tmp, &chan->desc_page, node) {
> > +               struct nbpf_link_desc *ldesc;
> > +               int i;
> > +               list_del(&dpage->node);
> > +               for (i = 0, ldesc = dpage->ldesc;
> > +                    i < ARRAY_SIZE(dpage->ldesc);
> > +                    i++, ldesc++)
> > +                       dma_unmap_single(dchan->device->dev, ldesc->hwdesc_dma_addr,
> > +                                        sizeof(*ldesc->hwdesc), DMA_TO_DEVICE);
> > +               free_page((unsigned long)dpage);
> > +       }
> > +}
> > +
> > +static int nbpf_slave_caps(struct dma_chan *dchan,
> > +                          struct dma_slave_caps *caps)
> > +{
> > +       caps->src_addr_widths = NBPF_DMA_BUSWIDTHS;
> > +       caps->dstn_addr_widths = NBPF_DMA_BUSWIDTHS;
> > +       caps->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
> > +       caps->cmd_pause = false;
> > +       caps->cmd_terminate = true;
> > +
> > +       return 0;
> > +}
> > +
> > +static bool nbpf_dma_filter(struct dma_chan *chan, void *param)
> > +{
> > +       return param == chan->device->dev->of_node;
> > +}
> > +
> > +static struct dma_chan *nbpf_of_xlate(struct of_phandle_args *dma_spec,
> > +                                     struct of_dma *ofdma)
> > +{
> > +       dma_cap_mask_t mask;
> > +       struct dma_chan *dchan;
> > +       struct nbpf_channel *chan;
> > +
> > +       if (dma_spec->args_count != 2)
> > +               return NULL;
> > +
> > +       dma_cap_zero(mask);
> > +       dma_cap_set(DMA_SLAVE, mask);
> > +
> > +       dchan = dma_request_channel(mask, nbpf_dma_filter, ofdma->of_node);
> > +       if (!dchan)
> > +               return NULL;
> > +
> > +       dev_dbg(dchan->device->dev, "Entry %s(%s)\n", __func__,
> > +               dma_spec->np->name);
> > +
> > +       chan = nbpf_to_chan(dchan);
> > +
> > +       chan->terminal = dma_spec->args[0];
> > +       chan->flags = dma_spec->args[1];
> > +
> > +       nbpf_chan_prepare(chan);
> > +       nbpf_chan_configure(chan);
> > +
> > +       return dchan;
> > +}
> > +
> > +static irqreturn_t nbpf_chan_irqt(int irq, void *dev)
> > +{
> > +       struct nbpf_channel *chan = dev;
> > +       struct nbpf_desc *desc, *tmp;
> > +       dma_async_tx_callback callback;
> > +       void *param;
> > +
> > +       while (!list_empty(&chan->done)) {
> > +               bool found = false, must_put, recycling = false;
> > +
> > +               spin_lock_irq(&chan->lock);
> > +
> > +               list_for_each_entry_safe(desc, tmp, &chan->done, node) {
> > +                       if (!desc->user_wait) {
> > +                               /* Newly completed descriptor, have to process */
> > +                               found = true;
> > +                               break;
> > +                       } else if (async_tx_test_ack(&desc->async_tx)) {
> > +                               /*
> > +                                * This descriptor was waiting for a user ACK,
> > +                                * it can be recycled now.
> > +                                */
> > +                               list_del(&desc->node);
> > +                               spin_unlock_irq(&chan->lock);
> > +                               nbpf_desc_put(desc);
> > +                               recycling = true;
> > +                               break;
> > +                       }
> > +               }
> > +
> > +               if (recycling)
> > +                       continue;
> > +
> > +               if (!found) {
> > +                       /* This can happen if TERMINATE_ALL has been called */
> > +                       spin_unlock_irq(&chan->lock);
> > +                       break;
> > +               }
> > +
> > +               dev_dbg(chan->dma_chan.device->dev,
> > +                       "%s(): chan %p #%d: cookie %d complete\n",
> > +                       __func__, &chan->dma_chan, chan - chan->nbpf->chan,
> > +                       desc->async_tx.cookie);
> > +               dma_cookie_complete(&desc->async_tx);
> > +
> > +               /*
> > +                * With released lock we cannot dereference desc, maybe it's
> > +                * still on the "done" list
> > +                */
> > +               if (async_tx_test_ack(&desc->async_tx)) {
> > +                       list_del(&desc->node);
> > +                       must_put = true;
> > +               } else {
> > +                       desc->user_wait = true;
> > +                       must_put = false;
> > +               }
> > +
> > +               callback = desc->async_tx.callback;
> > +               param = desc->async_tx.callback_param;
> > +
> > +               nbpf_cookie_success(chan, desc->async_tx.cookie);
> > +
> > +               /* ack and callback completed descriptor */
> > +               spin_unlock_irq(&chan->lock);
> > +
> > +               if (callback)
> > +                       callback(param);
> > +
> > +               if (must_put)
> > +                       nbpf_desc_put(desc);
> > +       }
> > +
> > +       return IRQ_HANDLED;
> > +}
> > +
> > +static irqreturn_t nbpf_chan_irq(int irq, void *dev)
> > +{
> > +       struct nbpf_channel *chan = dev;
> > +       bool done = nbpf_status_get(chan);
> > +       struct nbpf_desc *desc;
> > +       irqreturn_t ret;
> > +
> > +       if (!done)
> > +               return IRQ_NONE;
> > +
> > +       nbpf_status_ack(chan);
> > +
> > +       dev_dbg(&chan->dma_chan.dev->device, "%s()\n", __func__);
> > +
> > +       spin_lock(&chan->lock);
> > +       desc = chan->running;
> > +       if (WARN_ON(!desc)) {
> > +               ret = IRQ_NONE;
> > +               goto unlock;
> > +       } else {
> > +               ret = IRQ_WAKE_THREAD;
> > +       }
> > +
> > +       list_move_tail(&desc->node, &chan->done);
> > +       chan->running = NULL;
> > +
> > +       if (!list_empty(&chan->active)) {
> > +               desc = list_first_entry(&chan->active,
> > +                                       struct nbpf_desc, node);
> > +               if (!nbpf_start(desc))
> > +                       chan->running = desc;
> > +       }
> > +
> > +unlock:
> > +       spin_unlock(&chan->lock);
> > +
> > +       return ret;
> > +}
> > +
> > +static irqreturn_t nbpf_err_irq(int irq, void *dev)
> > +{
> > +       struct nbpf_device *nbpf = dev;
> > +       u32 error = nbpf_error_get(nbpf);
> > +
> > +       dev_warn(nbpf->dma_dev.dev, "DMA error IRQ %u\n", irq);
> > +
> > +       if (!error)
> > +               return IRQ_NONE;
> > +
> > +       do {
> > +               struct nbpf_channel *chan = nbpf_error_get_channel(nbpf, error);
> > +               /* On error: abort all queued transfers, no callback */
> > +               nbpf_error_clear(chan);
> > +               nbpf_chan_idle(chan);
> > +               error = nbpf_error_get(nbpf);
> > +       } while (error);
> > +
> > +       return IRQ_HANDLED;
> > +}
> > +
> > +static int nbpf_chan_probe(struct nbpf_device *nbpf, int n)
> > +{
> > +       struct dma_device *dma_dev = &nbpf->dma_dev;
> > +       int pdev_id = to_platform_device(dma_dev->dev)->id;
> > +       struct nbpf_channel *chan = nbpf->chan + n;
> > +       int ret;
> > +
> > +       chan->nbpf = nbpf;
> > +       chan->base = nbpf->base + NBPF_REG_CHAN_OFFSET + NBPF_REG_CHAN_SIZE * n;
> > +       INIT_LIST_HEAD(&chan->desc_page);
> > +       spin_lock_init(&chan->lock);
> > +       chan->dma_chan.device = dma_dev;
> > +       dma_cookie_init(&chan->dma_chan);
> > +       nbpf_chan_prepare_default(chan);
> > +
> > +       dev_dbg(dma_dev->dev, "%s(): channel %d: -> %p\n", __func__, n, chan->base);
> > +
> > +       if (pdev_id >= 0)
> > +               snprintf(chan->name, sizeof(chan->name),
> > +                        "nbpf %d.%d", pdev_id, n);
> 
> Is there real case when platform device created with explicit ID
> assignment?

Maybe not, can be removed.

> > +       else
> > +               snprintf(chan->name, sizeof(chan->name),
> > +                        "nbpf %d", n);
> > +
> > +       ret = devm_request_threaded_irq(dma_dev->dev, chan->irq,
> > +                       nbpf_chan_irq, nbpf_chan_irqt, IRQF_SHARED,
> > +                       chan->name, chan);
> > +       if (ret < 0)
> > +               return ret;
> > +
> > +       /* Add the channel to DMA device channel list */
> > +       list_add_tail(&chan->dma_chan.device_node,
> > +                     &dma_dev->channels);
> > +
> > +       return 0;
> > +}
> > +
> > +static const struct of_device_id nbpf_match[] = {
> > +       {.compatible = "renesas,nbpfaxi64dmac1b4",      .data = &nbpf_cfg[NBPF1B4]},
> > +       {.compatible = "renesas,nbpfaxi64dmac1b8",      .data = &nbpf_cfg[NBPF1B8]},
> > +       {.compatible = "renesas,nbpfaxi64dmac1b16",     .data = &nbpf_cfg[NBPF1B16]},
> > +       {.compatible = "renesas,nbpfaxi64dmac4b4",      .data = &nbpf_cfg[NBPF4B4]},
> > +       {.compatible = "renesas,nbpfaxi64dmac4b8",      .data = &nbpf_cfg[NBPF4B8]},
> > +       {.compatible = "renesas,nbpfaxi64dmac4b16",     .data = &nbpf_cfg[NBPF4B16]},
> > +       {.compatible = "renesas,nbpfaxi64dmac8b4",      .data = &nbpf_cfg[NBPF8B4]},
> > +       {.compatible = "renesas,nbpfaxi64dmac8b8",      .data = &nbpf_cfg[NBPF8B8]},
> > +       {.compatible = "renesas,nbpfaxi64dmac8b16",     .data = &nbpf_cfg[NBPF8B16]},
> > +       {}
> > +};
> > +MODULE_DEVICE_TABLE(of, nbpf_match);
> > +
> > +static int nbpf_probe(struct platform_device *pdev)
> > +{
> > +       struct device *dev = &pdev->dev;
> > +       const struct of_device_id *of_id = of_match_device(nbpf_match, dev);
> > +       struct device_node *np = dev->of_node;
> > +       struct nbpf_device *nbpf;
> > +       struct dma_device *dma_dev;
> > +       struct resource *iomem, *irq_res;
> > +       const struct nbpf_config *cfg;
> > +       int num_channels;
> > +       int ret, irq, eirq, i;
> > +       int irqbuf[9] /* maximum 8 channels + error IRQ */;
> > +       unsigned int irqs = 0;
> > +
> > +       BUILD_BUG_ON(sizeof(struct nbpf_desc_page) > PAGE_SIZE);
> > +
> > +       /* DT only */
> > +       if (!np || !of_id || !of_id->data)
> > +               return -ENODEV;
> > +
> > +       cfg = of_id->data;
> > +       num_channels = cfg->num_channels;
> > +
> > +       nbpf = devm_kzalloc(dev, sizeof(*nbpf) + num_channels *
> > +                           sizeof(nbpf->chan[0]), GFP_KERNEL);
> > +       if (!nbpf) {
> > +               dev_err(dev, "Memory allocation failed\n");
> > +               return -ENOMEM;
> > +       }
> > +       dma_dev = &nbpf->dma_dev;
> > +       dma_dev->dev = dev;
> > +
> > +       iomem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +       nbpf->base = devm_ioremap_resource(dev, iomem);
> > +       if (IS_ERR(nbpf->base))
> > +               return PTR_ERR(nbpf->base);
> > +
> > +       nbpf->clk = devm_clk_get(dev, NULL);
> > +       if (IS_ERR(nbpf->clk))
> > +               return PTR_ERR(nbpf->clk);
> > +
> > +       nbpf->config = cfg;
> > +
> > +       for (i = 0; irqs < ARRAY_SIZE(irqbuf); i++) {
> > +               irq_res = platform_get_resource(pdev, IORESOURCE_IRQ, i);
> > +               if (!irq_res)
> > +                       break;
> > +
> > +               for (irq = irq_res->start; irq <= irq_res->end;
> > +                    irq++, irqs++)
> > +                       irqbuf[irqs] = irq;
> > +       }
> > +
> > +       dev_dbg(dev, "%s(): mapped %x -> %p\n", __func__, iomem->start, nbpf->base);
> > +
> > +       /*
> > +        * 3 IRQ resource schemes are supported:
> > +        * 1. 1 shared IRQ for error and all channels
> > +        * 2. 2 IRQs: one for error and one shared for all channels
> > +        * 3. 1 IRQ for error and an own IRQ for each channel
> > +        */
> > +       if (irqs != 1 && irqs != 2 && irqs != num_channels + 1)
> > +               return -ENXIO;
> > +
> > +       if (irqs == 1) {
> > +               eirq = irqbuf[0];
> > +
> > +               for (i = 0; i <= num_channels; i++)
> > +                       nbpf->chan[i].irq = irqbuf[0];
> > +       } else {
> > +               eirq = platform_get_irq_byname(pdev, "error");
> > +               if (eirq < 0)
> > +                       return eirq;
> > +
> > +               if (irqs == num_channels + 1) {
> > +                       struct nbpf_channel *chan;
> > +
> > +                       for (i = 0, chan = nbpf->chan; i <= num_channels;
> > +                            i++, chan++) {
> > +                               /* Skip the error IRQ */
> > +                               if (irqbuf[i] == eirq)
> > +                                       i++;
> > +                               chan->irq = irqbuf[i];
> > +                       }
> > +
> > +                       if (chan != nbpf->chan + num_channels)
> > +                               return -EINVAL;
> > +               } else {
> > +                       /* 2 IRQs and more than one channel */
> > +                       if (irqbuf[0] == eirq)
> > +                               irq = irqbuf[1];
> > +                       else
> > +                               irq = irqbuf[0];
> > +
> > +                       for (i = 0; i <= num_channels; i++)
> > +                               nbpf->chan[i].irq = irq;
> > +               }
> > +       }
> > +
> > +       ret = devm_request_threaded_irq(dev, eirq, nbpf_err_irq, NULL,
> > +                                       IRQF_SHARED, "dma error", nbpf);
> 
> devm_request_irq since NULL ?

ok

> > +       if (ret < 0)
> > +               return ret;
> > +
> > +       INIT_LIST_HEAD(&dma_dev->channels);
> > +
> > +       /* Create DMA Channel */
> > +       for (i = 0; i < num_channels; i++) {
> > +               ret = nbpf_chan_probe(nbpf, i);
> > +               if (ret < 0)
> > +                       return ret;
> > +       }
> > +
> > +       dma_cap_set(DMA_MEMCPY, dma_dev->cap_mask);
> > +       dma_cap_set(DMA_SLAVE, dma_dev->cap_mask);
> > +       dma_cap_set(DMA_SG, dma_dev->cap_mask);
> > +
> > +       /* Common and MEMCPY operations */
> > +       dma_dev->device_alloc_chan_resources
> > +               = nbpf_alloc_chan_resources;
> > +       dma_dev->device_free_chan_resources = nbpf_free_chan_resources;
> > +       dma_dev->device_prep_dma_sg = nbpf_prep_memcpy_sg;
> > +       dma_dev->device_prep_dma_memcpy = nbpf_prep_memcpy;
> > +       dma_dev->device_tx_status = nbpf_tx_status;
> > +       dma_dev->device_issue_pending = nbpf_issue_pending;
> > +       dma_dev->device_slave_caps = nbpf_slave_caps;
> > +
> > +       /*
> > +        * If we drop support for unaligned MEMCPY buffer addresses and / or
> > +        * lengths by setting
> > +        * dma_dev->copy_align = 4;
> > +        * then we can set transfer length to 4 bytes in nbpf_prep_one() for
> > +        * DMA_MEM_TO_MEM
> > +        */
> > +
> > +       /* Compulsory for DMA_SLAVE fields */
> > +       dma_dev->device_prep_slave_sg = nbpf_prep_slave_sg;
> > +       dma_dev->device_control = nbpf_control;
> > +
> > +       if (np) {
> > +               ret = of_dma_controller_register(np, nbpf_of_xlate, pdev);
> > +               if (ret < 0)
> > +                       return ret;
> > +       }
> 
> I think it's better to call this after dma_async_device_register().

Yes, makes sense.

> > +
> > +       platform_set_drvdata(pdev, nbpf);
> > +
> > +       ret = clk_prepare_enable(nbpf->clk);
> > +       if (ret < 0)
> > +               goto e_of_unreg;
> > +
> > +       nbpf_configure(nbpf);
> > +
> > +       ret = dma_async_device_register(dma_dev);
> > +       if (ret < 0)
> > +               goto e_clk_off;
> > +
> > +       return 0;
> > +
> > +e_clk_off:
> > +       clk_disable_unprepare(nbpf->clk);
> > +e_of_unreg:
> > +       of_dma_controller_free(np);
> > +
> > +       return ret;
> > +}
> > +
> > +static int nbpf_remove(struct platform_device *pdev)
> > +{
> > +       struct nbpf_device *nbpf = platform_get_drvdata(pdev);
> > +
> > +       dma_async_device_unregister(&nbpf->dma_dev);
> > +       clk_disable_unprepare(nbpf->clk);
> > +       of_dma_controller_free(pdev->dev.of_node);
> > +
> > +       return 0;
> > +}
> > +
> > +static struct platform_device_id nbpf_ids[] = {
> > +       {"nbpfaxi64dmac1b4",    (kernel_ulong_t)&nbpf_cfg[NBPF1B4]},
> > +       {"nbpfaxi64dmac1b8",    (kernel_ulong_t)&nbpf_cfg[NBPF1B8]},
> > +       {"nbpfaxi64dmac1b16",   (kernel_ulong_t)&nbpf_cfg[NBPF1B16]},
> > +       {"nbpfaxi64dmac4b4",    (kernel_ulong_t)&nbpf_cfg[NBPF4B4]},
> > +       {"nbpfaxi64dmac4b8",    (kernel_ulong_t)&nbpf_cfg[NBPF4B8]},
> > +       {"nbpfaxi64dmac4b16",   (kernel_ulong_t)&nbpf_cfg[NBPF4B16]},
> > +       {"nbpfaxi64dmac8b4",    (kernel_ulong_t)&nbpf_cfg[NBPF8B4]},
> > +       {"nbpfaxi64dmac8b8",    (kernel_ulong_t)&nbpf_cfg[NBPF8B8]},
> > +       {"nbpfaxi64dmac8b16",   (kernel_ulong_t)&nbpf_cfg[NBPF8B16]},
> > +       {},
> > +};
> > +MODULE_DEVICE_TABLE(platform, nbpf_ids);
> > +
> > +#ifdef CONFIG_PM_RUNTIME
> > +static int nbpf_runtime_suspend(struct device *dev)
> > +{
> > +       struct nbpf_device *nbpf = platform_get_drvdata(to_platform_device(dev));
> > +       clk_disable_unprepare(nbpf->clk);
> > +       return 0;
> > +}
> > +
> > +static int nbpf_runtime_resume(struct device *dev)
> > +{
> > +       struct nbpf_device *nbpf = platform_get_drvdata(to_platform_device(dev));
> > +       return clk_prepare_enable(nbpf->clk);
> > +}
> > +#endif
> > +
> > +static const struct dev_pm_ops nbpf_pm_ops = {
> > +       SET_RUNTIME_PM_OPS(nbpf_runtime_suspend, nbpf_runtime_resume, NULL)
> > +};
> > +
> > +static struct platform_driver nbpf_driver = {
> > +       .driver = {
> > +               .owner = THIS_MODULE,
> > +               .name = "dma-nbpf",
> > +               .of_match_table = nbpf_match,
> > +               .pm = &nbpf_pm_ops,
> > +       },
> > +       .id_table = nbpf_ids,
> > +       .probe = nbpf_probe,
> > +       .remove = nbpf_remove,
> > +};
> > +
> > +module_platform_driver(nbpf_driver);
> > +
> > +MODULE_AUTHOR("Guennadi Liakhovetski <g.liakhovetski@xxxxxx>");
> > +MODULE_DESCRIPTION("dmaengine driver for NBPFAXI64* DMACs");
> > +MODULE_LICENSE("GPL v2");
> > diff --git a/include/dt-bindings/dma/nbpfaxi.h b/include/dt-bindings/dma/nbpfaxi.h
> > new file mode 100644
> > index 0000000..74f2054
> > --- /dev/null
> > +++ b/include/dt-bindings/dma/nbpfaxi.h
> > @@ -0,0 +1,20 @@
> > +/*
> > + * Copyright (C) 2013 Renesas Europe Ltd.
> > + * Author: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of version 2 of the GNU General Public License as
> > + * published by the Free Software Foundation.
> > + */
> > +
> > +#ifndef DT_BINDINGS_NBPFAXI_H
> > +#define DT_BINDINGS_NBPFAXI_H
> > +
> > +/**
> > + * Use "#dma-cells = <2>;" with the second integer defining slave DMA flags:
> > + */
> > +#define NBPF_SLAVE_RQ_HIGH     1
> > +#define NBPF_SLAVE_RQ_LOW      2
> > +#define NBPF_SLAVE_RQ_LEVEL    4
> > +
> > +#endif
> > -- 
> > 1.9.1
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe dmaengine" in
> > the body of a message to majordomo@xxxxxxxxxxxxxxx
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> 
> -- 
> Andy Shevchenko <andriy.shevchenko@xxxxxxxxx>
> Intel Finland Oy

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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